March 3, 2011

A panel of scientists recently unveiled new research funded by NOAA's Oceans and Human Health Initiative (OHHI) at the 177th annual meeting of the American Association for the Advancement of Science in Washington, DC. These three studies demonstrate how climate change could increase human-health risks originating from ocean, coastal, and Great Lakes ecosystems.

Hear two of the scientists from the panel discuss their work in this audio interview.

Climate Change and Harmful Algal Blooms

Stephanie Moore, Ph.D., of NOAA’s West Coast Center for Oceans and Human Health, together with partners at the University of Washington, used cutting-edge technologies to model future ocean and weather patterns. Their prediction? Longer seasons of Harmful Algal Bloom (HAB) outbreaks in Puget Sound, which could translate to longer shellfishery closings and threaten the state’s $108 million annual shellfish industry.

The team looked at blooms of Alexandrium catenella, commonly known as “red tide,” which produces a poison that can accumulate in shellfish. People who eat contaminated shellfish may experience gastrointestinal and neurological distress, including vomiting and muscle paralysis; in extreme cases, the illness can be fatal.

“Changes in the HAB season appear to be imminent and we expect a significant increase in Puget Sound and similar at-risk environments within 30 years, possibly by the next decade,” said Moore. “Our projections indicate that by the end of the 21st century, blooms may begin up to two months earlier in the year and persist for one month later compared to the present-day time period of July to October.”

Atmospheric Dust and the Ocean Environment

University of Georgia researcher Erin Lipp, Ph.D., and his colleagues considered how global desertification — the process by which fertile land turns into barren land or desert – and the resulting increase in atmospheric dust based on some climate-change scenarios could fuel the presence of harmful bacteria in the ocean and seafood. Lipp conducted the study in collaboration with the U.S. Geological Survey.

Desert dust from the atmosphere is one of the main contributors of iron in the ocean. While iron is essential to most forms of life, its presence is limited in the ocean environment. However, oceanic deposits of the heavy metal have increased over the last 30 years, and are expected to rise based on precipitation trends in western Africa. The researchers demonstrated that the sole addition of desert dust and its associated iron into seawater significantly stimulates the growth and persistence of Vibrios, a group of ocean bacteria that occur worldwide and can cause gastroenteritis and infectious diseases in people.

Vibrio cases have jumped 85 percent in the United States in the past 15 years, according to reports that track seafood illnesses. It is possible that the additional input of iron, in combination with rising sea surface temperatures, will affect these bacterial populations. This early research may help to explain both current and future increases in human illnesses from exposure to contaminated seawater and seafood.

Spring Rain, Aging Sewers, and Great Lakes Water Quality

Using fine-tuned climate models developed for the State of Wisconsin, Sandra McLellan, Ph.D., and her colleagues at the University of Wisconsin-Milwaukee School of Freshwater Sciences found that spring rains are expected to increase during the next 50 years, and those areas with dated sewer systems are more likely to overflow because the ground is frozen and rainwater cannot be absorbed. As little as 1.7 inches of rain in 24 hours can cause such overflows, and the combination of higher temperatures and increased precipitation can magnify the impacts, which include the release of disease-causing bacteria, viruses, and protozoa into drinking water and onto beaches.

The research revealed that in worst-case scenarios there could be an average 20 percent increase in the volume of sewage overflows. In Milwaukee, infrastructure investments have reduced sewage overflows to an average of three times per year, but some Great Lakes cities still experience as many as 40 per year.

“Hundreds of millions of dollars are spent on urban infrastructure, and these investments need to be directed to problems that have the largest impact on our water quality,” said McLellan. “Our research can shed light on this dilemma for cities with aging sewer systems throughout the Great Lakes and even around the world.”

NOAA Administrator Jane Lubchenco, PhD, praised the OHHI researchers and their findings. “NOAA and our partners are working to uncover how a changing climate can affect our health and prosperity,” she said. “These studies will better equip officials with the information and tools they need to prepare for and prevent risks associated with changing oceans and coasts.”